karaoke: midi file with additional information; some types can be imported

.kar

Stored midi parts, these are an alternative way of storing structures in muse.

.mpt

Stored plugin presets

.pre

Hint: In some versions < 0.6.3 MusE loaded the old configuration from ~/.musePrj or ~/.MusE and because it didn't work then you could have also tried removing or at least moving this files out of the way temporary for testing purposes.